A DC-to-DC converter is an electronic circuit which converts a source of direct current (DC) from one voltage level to another. A DC-to-DC converter can be categorized as a class of power converters.
DC-to-DC converters can be employed in portable electronic devices such as cellular phones and laptop computers, which are supplied with power from batteries primarily. Such electronic devices often contain several sub-circuits, each with its own voltage level requirement different from that supplied by the battery or an external supply (sometimes higher or lower than the supply voltage). Additionally, the battery voltage declines as the stored power in the battery is drained. Switched DC-to-DC converters can increase voltage from a partially lowered battery voltage.